The present invention relates to a method of desulphurization of a flue gas exhausted from boilers, industrial furnaces and the like and more particularly to a method of desulphurization of a flue gas which enables the operation of a desulphurizing apparatus or plant to be simplified. The present invention also relates to an improved desulphurizing apparatus having a simplified construction and a lowered production cost.
With the development of industry, the quantity of harmful gases, especially, sulphurous acid (SO.sub.2) and sulphuric acid anhydride (SO.sub.3) contained in the flue gas from a furnace in which sulphur-containing coal or heavy oil is burnt or in the flue gas from a sulphuric acid production plant, exhausted into the atmosphere along with the flue gas from various industrial facilities, is increasing and hence the air pollution in the vicinity of the facilities is increasing. As a result, the harmful effect of such gases on the inhabitants in the area of the facility is becoming a great social problem in recent years, and development of various types of flue gas treating apparatus is urgently desired.
As one such exhaust gas treating apparatus, an apparatus has been developed in which the sulphur oxides (SO.sub.2 and SO.sub.3) are separated and removed by passing the exhaust gas through an adsorption bed packed with activated carbon. The general techniques used in apparatus are known from U.S. Pat. No. 2,992,065, U.S. Pat. No. 2,992,895 and the technical treatise of Mr. F. Johswich, published on page 18 of Combustion, Oct. 1965, under the title of "The Present Status of Flue Gas Desulphurization".
A flue gas treating apparatus of adsorption bed type generally comprises a plurality of adsorption beds each being packed with activated carbon. After the activated carbon has become inactive to adsorb the sulphur oxide, the adsorption beds must be regenerated or recovered by a suitable manner such as washing down the activated carbon.
In the conventional regeneration methods a regenerating liquid such as water or a dilute sulphuric acid solution is supplied to an adsorption bed to be regenerated after the flue gas inlets thereof are closed. After the regeneration or washing down of the activated carbon has finished, the flue gas inlets are opened again.
Since the operation of the flue gas inlets has inevitably to be performed in a cycle at a certain time interval and in an actual apparatus the valve of the flue gas to be treated is extremely large, the switching operation of the valve means provided in the flue gas inlets requires considerable labor or elaborate control devices.